1. Field of the Invention
The present invention relates to spinal implants for implantation between a pair of adjacent vertebrae in order to provide support to the vertebrae and/or promote bone fusion between the vertebrae.
2. Background Information
Because of disease, injury or deformity the disc that is between adjacent vertebrae of the human spine may become damaged. Additionally, the disc may simply deteriorate due to age or congenital defect. In these and in other circumstances, one or more vertebrae may become compressed or otherwise damaged. Moreover, the vertebrae can become too closely spaced which causes an undesired abnormal curvature of the spine. Such conditions may also cause a nerve to be pinched, creating pain, numbness and/or other symptoms. In these situations it is then necessary to provide support and/or alignment to and between adjacent vertebrae of the patient's spine. This is generally accomplished through spinal surgery.
With spinal surgery, one or more spinal implants, spacers, intervertebral devices or interbody devices (collectively, interbody devices) are placed between adjacent vertebrae once the disc has been removed. This provides proper spacing of the vertebrae. The interbody device may also promote fusion between the adjacent vertebrae.
Once the interbody device has been implanted into the intervertebral space, it is important that the interbody device remain in its implanted position. This is accomplished by using bone screws that extend through the interbody device and into the vertebral bone. Typically, one or more bone screws extend through the interbody device and into vertebral bone of an upper, adjacent vertebra and a lower, adjacent vertebra. Because the bone screws are oriented in a particular manner in order to fix the interbody device relative to and between the adjacent vertebrae, it is vital that the bone screws do not back out while implanted.
Accordingly, there exists a need for an interbody device that remains in place once implanted and provides stabilization and torsional resistance in order to promote vertebral fusion. Moreover, there exists a need for an interbody device that retains its bone screws once installed.